President Trump on Thursday doubled down on his idea of arming some teachers as a deterrent for school shootings and praised the top leadership of the National Rifle Association as “Great American Patriots.”

In morning tweets and later in a “listening session” at the White House, Trump claimed the strategy of arming teachers would be far less costly than hiring guards. He said “gun-free” school zones make it like “going in for ice cream” for school shooters and said on Twitter that with his strategy, “ATTACKS WOULD END!”

His remarks amplified a strategy Trump pushed during a first “listening session” Wednesday at the White House, which included relatives of some of the 17 people killed by a gunman last week at Marjory Stoneman Douglas High School in South Florida. Thursday's session included law enforcement officers and other officials.

“Highly trained, gun adept, teachers/coaches would solve the problem instantly, before police arrive,” Trump said in one morning tweet.

During the “listening session” a couple of hours later, Trump said he wants “my schools protected just like I want my banks protected.”

The strategy of arming teachers has many critics, including some law enforcement officers and the National Education Association, the country’s largest teachers lobby. In a statement Wednesday, NEA president Lily Eskelsen García said, “Educators need to be focused on teaching our students.”

In his tweets, Trump claimed his strategy had been mischaracterized by some news outlets and is more nuanced than reported. He said he envisioned only about 20 percent of teachers having concealed weapons and said they would have “military or special training experience.”

“If a potential ‘sicko shooter’ knows that a school has a large number of very weapons talented teachers (and others) who will be instantly shooting, the sicko will NEVER attack that school,” Trump said. “Cowards won’t go there ... problem solved. Must be offensive, defense alone won’t work!”

Some criminologists have questioned that reasoning, pointing out that some people who plan to commit mass shootings are prepared to die in the process.

“What many people don’t understand, or don’t want to understand, is that Wayne, Chris and the folks who work so hard at the @NRA are Great People and Great American Patriots,” Trump wrote. “They love our Country and will do the right thing.”

“MAKE AMERICA GREAT AGAIN!” Trump added.

In the aftermath of the shooting, Trump has publicly and privately floated actions that would be at odds with the positions of the NRA, one of his biggest supporters in the 2016 campaign.

In a separate tweet Thursday, Trump appeared to highlight one of those conflicts: raising the age for purchasing assault rifles from 18 to 21.

“I will be strongly pushing Comprehensive Background Checks with an emphasis on Mental Health. Raise age to 21 and end sale of Bump Stocks!” Trump said in the tweet. “Congress is in a mood to finally do something on this issue — I hope!”

In a statement this week, NRA spokeswoman Jennifer Baker noted that federal law prohibits anyone younger than 21 from purchasing a handgun from a licensed firearms dealer.

“Legislative proposals that prevent law-abiding adults aged 18-20 years old from acquiring rifles and shotguns effectively prohibits them for purchasing any firearm, thus depriving them of their constitutional right to self-protection,” Baker said.

Trump said during Friday's listening session that he thought the NRA would support raising the age to 21.

“I don't think I'll be going up against them. ... They're good people,” said Trump, who also praised the organization more broadly. “The NRA is ready to do things. People like to blame them.”

Vice President Pence did not mention increasing the minimum age as he addressed the Conservative Political Action Conference, which is being held in the Washington area this week.

Instead, Pence pointed to Trump's call for members of Congress to “strengthen background checks” and for the Justice Department to expedite new regulations for “bump stocks,” devices that can convert a legal semiautomatic weapon into one that fires like a fully automatic one.

Pence said “the safety of our nation's schools and our students” is a top national priority, and the administration wants to provide law enforcement and American families “the tools they need to deal with those struggling with dangerous mental illness.”

Earlier this week, Trump directed Attorney General Jeff Sessions to propose regulations to ban bump stocks and other devices that turn semiautomatic firearms into “machine guns.” A bump stock was used by the shooter who opened fire on a country music festival in Las Vegas in October, killing 58 people and wounding hundreds of others. That massacre immediately prompted calls for lawmakers or the administration to ban such devices through legislation or regulations, but efforts to pass a ban stalled in Congress.

In an appearance Thursday morning on Fox News, White House counselor Kellyanne Conway said none of the ideas floated during Thursday’s meeting has been finalized and she criticized reports focusing on arming teachers.

“To focus on that alone today is disingenuously covering the fuller discussion yesterday, and frankly, it’s disrespectful to the people who were in that room raising any number of different issues,” Conway said.

I never said “give teachers guns” like was stated on Fake News @CNN & @NBC. What I said was to look at the possibility of giving “concealed guns to gun adept teachers with military or special training experience - only the best. 20% of teachers, a lot, would now be able to

....immediately fire back if a savage sicko came to a school with bad intentions. Highly trained teachers would also serve as a deterrent to the cowards that do this. Far more assets at much less cost than guards. A “gun free” school is a magnet for bad people. ATTACKS WOULD END!

....History shows that a school shooting lasts, on average, 3 minutes. It takes police & first responders approximately 5 to 8 minutes to get to site of crime. Highly trained, gun adept, teachers/coaches would solve the problem instantly, before police arrive. GREAT DETERRENT!

....If a potential “sicko shooter” knows that a school has a large number of very weapons talented teachers (and others) who will be instantly shooting, the sicko will NEVER attack that school. Cowards won’t go there...problem solved. Must be offensive, defense alone won’t work!

I will be strongly pushing Comprehensive Background Checks with an emphasis on Mental Health. Raise age to 21 and end sale of Bump Stocks! Congress is in a mood to finally do something on this issue - I hope!

A Washington Post-ABC poll published this week found that 51 percent of Americans said the school shooting in Parkland “could not have been prevented” by allowing schoolteachers to carry guns, while 42 percent said it could have been prevented.

A larger majority, 58 percent, said stricter gun-control laws could have prevented the event, and 77 percent said better mental health screening and treatment could have thwarted it.

Trump has offered no details on how a program of arming teachers would work, how much it would cost and how school districts already strapped for cash would fund it. The Education Department estimates there are 3.1 million public school teachers and 400,000 private-school teachers. Arming 20 percent of teachers would mean arming more than 700,000 people. (There were about 1.3 million active-duty U.S. military personnel in 2016.)

In Thursday's listening session, Trump called his chief of staff, John F. Kelly, a “tough cookie” and told participants that if Kelly were his teacher, he would want Kelly to have a gun.

Speaking to reporters afterward, Florida Attorney General Pam Bondi (R), one of the participants, said there is a need for more protection of students in schools.

“If teachers are armed … they must be highly trained, highly qualified or acting like air marshals, in a capacity like that — former police, former military, coming in in some capacity like that, where they are extremely qualified,” Bondi said. “Not just giving every teacher in school a handgun to carry. I don’t believe that’s going to happen. I don’t think anyone wants that to happen.”

The idea of arming teachers is not a new one for Trump, who often responds to mass shootings by proposing an increase in the number of law-abiding citizens who carry firearms and can stop a shooter.

In July 2015, following a shooting at a military recruitment center in Tennessee that left four Marines dead, Trump tweeted in all caps: “MILITARY LIVES MATTER! END GUN FREE ZONES! OUR SOLDIERS MUST BE ABLE TO PROTECT THEMSELVES! THIS HAS TO STOP!”

In November 2015, after terrorist attacks in and near Paris that left 130 people dead, Trump criticized the city for having “the toughest gun laws in the world.”

“Nobody had guns but the bad guys. Nobody had guns. Nobody,” Trump said at the time at a campaign rally.

In December 2015, after a mass shooting in Southern California that left 14 dead, Trump told reporters in Iowa the victims of the shooting “could've protected themselves if they had guns.”

“If you look at what happened in California, they didn't have guns, and they were slaughtered,” Trump said.

In January 2016, Trump said at a campaign rally in Vermont that he wants to eliminate gun-free zones at schools.

“I will get rid of gun-free zones on schools, and — you have to — and on military bases,” Trump said, to scattered cheers. “My first day, it gets signed, okay? My first day. There's no more gun-free zones.”

In June 2016, after a mass shooting at a Florida nightclub, Trump said, “It's too bad some of the people killed over the weekend didn’t have guns attached to their hips, where bullets could have thrown in the opposite direction.” He said “had people been able to fire back, it would have been a much different outcome.”

“If some of those wonderful people had guns strapped right here — right to their waist or right to their ankle — and one of the people in that room happened to have it and goes 'boom, boom,' you know, that would have been a beautiful sight, folks,” Trump said in a radio interview at the time.

At the time, even leaders of the NRA said arming drunk clubgoers was a bad idea. Trump then clarified his comment and said he “was obviously talking about additional guards or employees.”